<mat-toolbar color="primary" class="header">
  Easy-Viewer
  <section class="btn-container">
    <button mat-button [matMenuTriggerFor]="loadTile">加载模型</button>
    <button mat-button (click)="toggleSideState()">数据列表</button>
  </section>
</mat-toolbar>
<mat-menu #loadTile="matMenu">
  <button mat-menu-item (click)="useUrl()">输入路径</button>
  <button mat-menu-item (click)="selectFile()">本地文件</button>
</mat-menu>
